Pseudocyanine dye



Patented Sept. 9, 1941 UNlT rrrs 2,255,128 PSEUDOCYANINE DYE Uskar Riester, Dessau, Germany, assignor, by mesne assignments, to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing.

Application March 9, 1938, Serial N0. 194,838.v In Germany March 13,1937

4 Claims.

My present invention relates to new dyes of i the pseudocyanine series.

It is already known to sensitize silver halide emulsions by means of oxopseudocyanines. An object of the present invention is the provision of substituted benzoxopseudocyanines. Further objects will be seen from the detailed specification following hereinafter. i

This invention is based on the discovery that the benzoxocyanines substituted in the 5-position by a phenyl group havea superior sensitizing effect in the greenor the blue-green portion of the spectrum.

The quinoline nucleus in the pseudocyanine dyestuii may be substituted by known substituents for example by alkyl, oxalkyl. The 5-phenylbenzoxazole serving as the parent material may be produced as follows:

Para-oxydiphenyl is nitrated, whereby the nitro-group enters into ortho-position relatively to the oxy-group. By the formation of the oxazole the position of the nitro-group is generally settled (compare Annalen 207, page 351, Annalen 209, page 348). The nitro-compound may be separated from dye-products by distillation with steam. For making the amino-compound the nitro-compound is reduced, for instance with sodium hydrosulphite in alkaline solution. The amino-compound is then converted into the oxazole by distillation with acetic anhydride.

thereof is converted into the quaternary ammonium salt in the usual manner by heating it Furthermore, it is possible with alkyl iodide or another alkyl ester. The quaternary salt may be converted by known methods into the pseudocyaninesl' Instead of 5-phenyl-2-alkylbenzoxazole there may be used. a 5-pheny1-2-alkylbenzoxazole containing as a substituent in the 6-position a methyl or oXalkyl-group.

The following examples illustrate the present invention, but they are not intended to limit it thereto: r Example 1 0 with N-ethylthio-G-methoxy-quinoline ethylio dide in pyridine corresponds with the following formula:

7 O OCH:

sensitizing maximum, 5000 A. E.

Example 3 A pseudo'cyanine produced by condensing the 5-phenyl 2 methyl benzoxazole methyliodide with N-ethylthio-7-ethoxy-quinoline ethyliodide in pyridine corresponds with the following formula:

sensitizing maximum, 4950 E.

Example 4 A pseudocyanine produced by condensing the 5-pheny1-2-methyl-benzoxazole propyliodide with N-propy1thio-6-methoxy-quinoline-ethyliodide in pyridine corresponds with the following formula:

(II-CH- N f O OCH:

sensitizing maximum, 5100 A. E.

Example 5 sensitizing maximum, 5050 A. E.

Moreover these dyes have sharply limited regions of sensitizing effect and are therefore very suitable for various special purposes, especially for color photography and in the particular for processes in which multi-layer color sensitized material is used. They have also the advantage that they are. insensitive to dyestufi components such as are used in the emulsion in various multilayer processes. 7

The operation of sensitizing photographic silver halide emulsions with these dyes is conducted in the usual manner by adding the dyestufi to the emulsion at any stage of its production or by bathing the layer of emulsion in a solution of the dyestufi diluted to the usual extent.

I claim:

1. A pseudocyanine dye having the following structure:

2. A pseudocyanine dye having the following structure:

3. A pseudocyanine dye having the following structure:

4. A cyanine dye salt of the formula i X N N/ alkyl alkyl anion wherein X is selected from the class consisting of hydrogen, alkyl and alkoxy, one X always being hydrogen.

OSKAR RIES'IER. 

